Telegraphy transmitter



Feb. 1, 1-944. NI 2,340,590

TELEGRAPH! TRANSMITTER v Filed Nov, 15, 1940 mm F lil

y g C qrrenf Padio Means S Fansmiiier as r if B E 5 flzierzmfiny CurrentRadio Source Wansmizfer INQVEIISITOR FRITZ HE/ N/G ATTORNEY 7 Fil q]Patented Feb. 1, 1944 TELEGRAPHY TRANSMITTER Fritz Hennig, Berlin,Germany; vested in the Alien Property Custodian Application November 15,1940, Serial No. 365,744 In Germany October 13, 1939 2 Claims.

In keying radio transmitters with telegraph devices check-up receptionby radio is not always feasible. This, in the first place, is impossiblewhen no receiver apparatus is available. Moreover, where the transmitterand the receiver are quite close together so that, for instance, theyhave a joint antenna and ground, or a joint source of current supply, acoupling may arise between the transmitter and the receiver of such anature that the telegraphic signals are vitiated or obliterated in thereceiver. The monitor record will accordingly become unclean orillegible and will not provide an accurate indication of the messagebeing sent out. In all of these instances the check-up of the messagemust be made locally, in other words, the circuitous way through radiotransmitter and receiver is not feasible.

The keying circuit of radio telegraphic transmitters is often designedfor direct current and is so operated, for instance, that the keyingcontact or the telegraphic transmitter opens the closed direct currentcircuit to key the transmitter. Reception, however, is mostly carriedout by use of a keyed tonal-frequency circuit at the receiver.

Now, according to the invention, operation of these different circuitsis made feasible in a simple way by causing a single telegraphic keyerto key simultaneously several circuits in which currents of differentkind are flowing. One of th keyed currents is used to control thetransmitter, the other keyed current being used to operate a receiver ormonitor to check up on the message.

In instances as hereinbefore mentioned, the various circuits arepreferably connected in parallel in relation to the telegraphictransmitter, while the alternating current of one of the circuits isexcluded by suitable stopper circuit means in the other circuit. Thedirect current is kept out of the alternating current circuit by acondenser included therein.

For the sake of simplication, under certain operating conditions, whichshall be explained more fully hereinafter, it is possible also to resortto a pure series arrangement of all circuit elements. The radiotransmitter is then blocked ofi by means of a condenser for thetonal-frequency signals, the said condenser being connected in parallelrelation to the output terminals.

Figs. 1 and 2 of the appended drawing illustrate exemplified embodimentsof the invention which show further details of the scheme.

The keying circuit of the radio transmitter DS starts from battery B andruns through the telegraphic signal transmitter or keying means TS,stopper circuit F to the radio transmitter DS. i'Ihis stopper circuit Fmay be as shown a parallel circuit parallel resonant to the tonalfrequency supplied by source S. The telegraphic device TS may consist,for instance, of a picture point scanner and transmitter drum. Thetonalfrequency circuit starts at the source of tone current supply S andruns through condenser C, telegraphic transmitter TS, primary winding I0of transformer U and back to the said source of supply S. When sendingthrough the telegraphic instrument TS both circuits are keyed. Theentrance of direct current into the tonalfrequency circuit is precludedby condenser C, while stopper or rejector circuit F precludes tonalfrequency from the direct-current circuit. The telegraphic receiver,used here to check-up on the message, is united with terminals TE.

In the case of the embodiment shown in Fig. 2, the assumption is madethat the direct-current resistance of theprimary winding IU oftransformer U and of the source of tonal frequency S is very low. Inthis case, both may be looped in the direct current keying circuit ofthe radio transmitter without any appreciable drop or loss of directcurrent being incidentally occasioned. The direct-current impulses inthe primary winding ID of transformer U will not affect the monitorrecord. Condenser C short-circuits the input end of the radiotransmitter DS for impulses of tonal frequency from source S. Aresistance R is provided for insuring current limitation. Thus, in thiscircuit arrangement mutual disturbance or interference of thedirect-current and tonal-frequency impulses is avoided.

What is claimed is:

1. In a telegraphy system, a transmitter circuit, a receiver circuit, asource of current of varying amplitude, a source of direct current, asingle keyer in circuits coupling one of said sources to saidtransmitter circuit and the other e of said sources to said receivercircuit, means in said circuits for preventing current from said sourcecoupled to said transmitter circuit from reaching said receiver circuit,and means in said circuits for preventing current from said sourcecoupled to said receiving circuit from reaching said transmittercircuit.

2. In a system for producing signalling energy and for monitoring thesaid signalling energy as produced, a source of direct current, a sourceof current of varying amplitude, a keyer, a transmitter circuit, amonitor circuit, a direct current circuit, including said keyer anddirect current source in series, coupled to said transmitter circuit, avariable amplitude current circuit including said source of current ofvariable amplitude and said keyer in series, coupled to said monitorcircuit, a variable current stopper in said direct current circuit and adirect current stopper in said variable current circuit.

FRITZ HENNIG.

